1. Field of the Invention
This invention relates to a rope, more particularly to a safety elastic rope which has an elastic outer tubular rope and an inner rope.
2. Description of the Related Art
A conventional elastic rope 11 is commonly used to form an exercising device 1 (see FIG. 1) for performing various exercises. In some instances, the elastic rope 11 is connected to a stationary exercise machine (not shown). Since the elastic rope 11 is made of a rubber-based material, such as natural rubber, thermoplastic rubber (TPR), etc., it oxidizes easily, and thus breaks easily. Particularly, when the exercising device 1 is stored, the elastic rope 11 is usually rolled up, so that oxidation easily occurs in bending portions of the elastic rope 11. When the elastic rope 11 is removed from storage and used, it may break and, in some cases, inflict injury on the user.
To overcome the aforementioned drawback, referring back to FIG. 1, a nylon woven sleeve 12 is sleeved on an outer portion of the conventional elastic rope 11. When the elastic rope 11 breaks, it is constrained within the nylon woven sleeve 12, and is not likely to be directed toward the user and inflict injury. Since the nylon woven sleeve 12 is not elastic, the length of the nylon woven sleeve 12 must be longer than that of the elastic rope 11, so that the elastic rope 11 can be stretched and used effectively. However, prior to stretching of the elastic rope 11, the nylon woven sleeve 12 is collected on the outer portion of the elastic rope 11 and forms an irregular crease. This adversely affects the appearance of the elastic rope 11. Further, the conventional elastic rope 11 with the nylon woven sleeve 12 sleeved thereon is not suitable for use in other exercising devices.
Moreover, the length of the elastic rope 11 when stretched is generally about eight to ten times its original unstretched length. If such a length of the nylon woven sleeve 12 is to be used, i.e., eight to ten times the original length of the elastic rope 11, the accumulation of the nylon woven sleeve 12 on the outer portion of the elastic rope 11 will be substantial when the elastic rope 11 is long. Hence, in order to reduce the amount of accumulation and the material cost of the nylon woven sleeve 12, and to allow the elastic rope 11 to be suitable for used on various exercising devices, a length of the nylon woven sleeve 12 that is about four times the original length of the elastic rope 11 is frequently used. In this case, when the elastic rope 11 is stretched to a length greater than that of the nylon woven sleeve 12, the nylon woven sleeve 12 may break or tear and may therefore lose its protection capability.